1. Field of the Invention
The present invention relates to a passenger protecting device, such as an air bag inflating unit and a seat belt tensing unit, and particularly, it relates to an improvement of communicating method for information about a passenger on a vehicle.
2. Description of the Related Art
Japanese Patent Publication No. 10-175503 discloses a passenger protecting device which detects the passenger""s situation at the vehicle""s collision and also determines the inflating conditions of an air bag.
In the passenger protecting device of this kind, informations about the presence of a seated passenger, the passenger""s seating position, the presence of a child seat on the seat, etc. are collected by means of a load sensor, a position sensor, etc. Upon overall judgement with reference to these informations, the passenger protecting device further controls a pressure for inflating the air bag. In detail, when the assistant driver""s seat is not occupied with a passenger or when the child seat has been set up on the assistant driver""s seat, the air bag is not inflated in spite of the vehicle""s collision. Further, when the passenger just after the vehicle""s collision is tumbling forward to the vehicle front or when the seat belt has been fastened over the passenger, the air bag is inflated under a reduced inflating pressure at the vehicle""s collision.
Meanwhile, as to the collection of various informations by means of some terminal units disposed in the driver""s seat and the assistant driver""s seat, it should be noted that the information about the presence of the passenger on seat, the presence of the child seat, etc. does not alter before and after the vehicle""s collision at all. Thus, even if this kind of information is collected at relatively long intervals, there would be no problem. On the contrary, the information about the passenger""s seating position etc. continuously changes during the vehicle""s traveling. Particularly, such information greatly alters before and after the vehicle""s collision. Thus, due to the high priority, such information has to be collected at relatively short intervals.
Therefore, it will be expected of a communication method where both communication object and period are changed so that the communication units is normally performed with all of terminal units at relatively long communication intervals, while the communication with the terminal unit of high priority is performed at relatively short communication intervals once the vehicle""s collision is detected. However, if the communication object and period are not changed at the vehicle""s collision certainly, there would be occurred a situation where the information about the passenger""s position just after the vehicle""s collision, which is required for determining the inflating pressure of air bag, is not obtained. Consequently, it is difficult to determine when the communication object and period should be changed.
Under such a circumstance, it is an object of the present invention to provide a passenger protecting device which is capable of collecting informations for determining the conditions for operating a passenger protecting unit, through terminal units at appropriate cycles corresponding to the information priority, without changing the communication method with the plural terminal units before and after the vehicle""s collision.
According to the invention, the above-mentioned object is accomplished by a passenger protecting device for a vehicle, comprising:
a passenger protecting unit to be arranged in the vicinity of a passenger on the vehicle, for protecting the passenger;
a plurality of terminal units arranged in the vehicle, for detecting a plurality of information about the passenger and a loadage on the seat; and
a central control unit which communicates with the plural terminal units through a single communication line at intervals of a predetermined cycle thereby to collect the plural information and which determines the operating condition of the passenger protecting unit and also controls the operation of the passenger protecting unit;
wherein the central control unit carries out the communication with at least one terminal unit detecting an information of high priority at every interval of the predetermined cycle and also carries out the communication with the other terminal units detecting other information of low priority in sequence at intervals of the predetermined cycle.
The above and other features and advantages of this invention will become apparent, and the invention itself will best be understood, from a study of the following description and appended claims, with reference to the attached drawings showing one preferred embodiment of the invention.